This invention relates to chemical lasers and more particularly to a continuous wave (cw) carbon monoxide laser fueled by carbon monosulfide.
A review of the state of the art of chemical lasers is contained in an article by Arthur N. Chester entitled `Chemical Lasers: A Survey of Current Research` published in Proceedings of the IEEE, Vol. 61, No. 4, April 1973. Patent No. 3,760,293 describes a continuous wave free burning flame laser using carbon disulfide and oxygen as reactants.
In a conventional carbon disulfide -- oxygen laser the oxygen molecule is dissociated into reactive oxygen atoms, and the carbon disulfide reacts with an oxygen atom to produce carbon monosulfide and sulfur monoxide. This reaction at temperatures of less than 500.degree. K. is represented as follows: EQU CS.sub.2 + O .fwdarw. CS + SO - 21.5 kcal/mole
The carbon monosulfide reacts with an oxygen atom to produce carbon monoxide laser emission as follows: EQU O + CS .fwdarw. CO* + S - 85 kcal/mole
It is reported that about 75% of the exothermicity enters vibration of CO.
A final reaction in this system results in regeneration of oxygen atoms as follows: EQU S + O.sub.2 .fwdarw. SO + O - 6 kcal/mole
The reaction O + CS.sub.2 .fwdarw. CS + SO acts primarily as a rate-limiting step to the pumping reaction in a CO chemical laser, and its exothermicity is detrimental to the medium because of the temperature dependence of CO optical gain coefficients. An additional and more subtle effect of increased temperature is to speed V--V relaxation rates in CO--CO collisions, and thus hasten V--V equilibration of the CO vibrational distribution, which also leads to decreased optical gain coefficients.
Of the 85 kcal/mole produced in the O + CS .fwdarw. CO* + S reaction, only some 21.2 kcal/mole is supplied to translational and rotational modes. This is a relatively small amount compared to the total reaction exothermicity.
Carbon monosulfide is not a radical species in the usual sense, and it exhibits long lifetimes at low pressures. Therefore, it is a feasible fuel for use directly in a CO chemical laser. Elimination of the reaction between carbon disulfide and oxygen will increase the rate of the pumping reaction by about a factor of 4, and the heating of the laser medium will be reduced to about a factor of 2.
The apparatus used in this invention is described in an article by William Q. Jeffers (a co-inventor of this application) in Appl. Phys. Letters 21, 267 (1972).